Pipeline flaw detector and marker



v March l, 1966 F. M. woon ETAL PIPELINE FLAW DETECTOR AND MARKER FiledJune 6, 1961 m MM lll

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ATTORNEYS United States Patent O PTPELINE FLAW DETECTOR AND MARKERFenton M. Wood and Harold J. Schneider, Houston, Tex.,

assignors, by mesne assignments, to American Machine & Foundry Company,New York, N.Y., a corporation of New Jersey Filed June 6, 1961, Ser. No.115,243 11 Claims. (Cl. 324-37) This invention relates to the inspectionof ferromagnetic goods and, more particularly, to a method and apparatusfor detecting aws in a pipeline and marking the location of such aws sothat a repair crew can accurately locate those portions of the pipelinecontaining the flaws.

While a relatively short tube or pipe can be inspected successfully withrelative ease by means of several types of devices currently available,more severe problems arise when the work to be inspected is a pipelinewhich is several miles long and which may be buried in the ground. Ininspecting a long pipeline, the inspection apparatus is normallyinserted as a unit for bodily movement through the pipeline. Once withinthe pipe-line, the inspection apparatus must function automatically toinspect the entire length of the pipeline to accurately locate any flawswhich might exist in the pipeline so that the necessary repair can bemade to prevent failure of the pipeline due to such flaws.

Accordingly, one of the objects of this invention is to provide animproved method and apparatus for inspecting elongated ferromagneticgoods to locate any aws within such goods.

Another object is to provide an improved method and apparatus fordetecting flaws in a pipeline and marking the location of such tlaws.

Still another object is to provide an improved inspection method andapparatus for magnetically marking the leations of flaws, if any, withina tubular ferromagnetic object.

Yet another object is to provide inspecion apparatus for inspecting anelongated pipeline to determine and mark the location of any flawswithin the pipeline, which apparatus is dependable and requiresrelatively low amounts of power for operation.

In order that the manner in which these and other objects are attainedin accordance with the invention can be understood in detail, referenceis had to the accompanying drawing, which forms a part of thisspecitcation, and wherein:

FIG. l is an elevational view, partly in section, illustrating oneembodiment for carrying out the method of the invention;

FIG. 2 is a transverse sectional view taken generally along line 2-2 ofF-IG. 1; and

FIG. 3 is a block diagram illustrating some of the electrical componentsof the embodiment shown in FIG. 1.

In accordance with the method of the invention, the location of -a Hawin an elongated ferromagnetic rnember such as a pipe line offerromagnetic material is marked by simultaneously passing through thepipeline both a lflaw detecting device and an electromagnet. Any awswhich exist in the pipeline are detected by the ilaw detecting device.When a flaw is detected, the electromagnet is actuated tocharacteristically magnetize the pipeline to provide an indication ofthe location of the detected aw.

One advantageous embodiment for carrying out the invention isillustrated in the drawing. Referring to FIGS. 1 and 2, there is shown aportion of a pipeline of the type used by the oil industry to conveyfluids over relatively long distances, the pipeline being offerromagnetic material -such as steel. Pipeline inspection 3,238,448Patented Mar. 1, 1966 apparatus 11 is disposed in pipeline 10 formovement therethrough over the length being inspected, such apparatusybeing inserted into the pipeline in any usual fashion.

Means are provided for passing the inspection apparatus through thepipeline, such means including a conventional gas seal 12 in the form ofa cup-shaped plug of resilient material having a rearwardly extendinglip 13. Fluid pressure is applied against the left end of the seal asviewed in FIG. 1, so that the `lip engages the kadjacent portion of theinner wall of pipeline 10 and thereby creates a pressure differentialwhich, acting upon the gas seal, propels the apparatus through thepipeline to the right and in the `direction of the arrow as viewed inFIG. l. It is obvious that the uid pressure within the pipe to vtheright of seal 12 must be lower than that to the left of the seal inorder to eiect the necessary movement.

The leading end of gas seal 12 is connected to the trailing end of anelectromagnet 14 having a pair of cy- -lindrical poles `15 and 16interconnected lby a cylindrical core 17 upon which an energizing coil18 is wound. Poles 15 and 16 and core 17 are supported coaxially withpipeline 10, the diameters of poles 15 and 16 being less than that ofthe internal diameter of the pipeline. The diameter of core 17 is lessthan that of poles 15 and 16. The electromagnet is operative, uponenergization of coil 18, to create a magnetic field which passes throughthe walls of pipe 10, the eld being of Sufficient strength topermanently magnetize such portions of the pipeline and therebyestablish a magnetic eld of a given polarity which extends for adistance of several yards around the pipeline so that the field can bedetected by a magnetometer. Where the pipeline is buried several feetunderground, it is obvious that the lstrength of the iield induced inthe pipeline must be suilicient to extend above the surface of theground and thereby enable the magnetometer to indicate the presence ofsuch iield.

The leading end of electromagnet 14 is connected to the trailing end ofa cylindrical housing 19 which encloses the power supply used to operatecomponents of the apparatus. The power supply can be in the form ofbatteries or a turbo-generator actuated by the iluid pressure used topropel the apparatus through the pipeline. An annular flange 20 issecured to the outer surface of housing 19 and bears against a helicalcompression spring 21 which, in turn, bears against a ring 22 connectedto bias a plurality of centralizing wheels 23 into contact with theinner wall of pipeline 10 so that the apparatus moves through thepipeline generally along the axis thereof. Each of wheels `23 issupported by a pair of arms 24 xedly secured at one end to housing `19and by a pair of arms 25 pivotally connected to ring 22. Ring 22 isslidable along housing 19 so that wheels 23 are maintained in engagementwith the wall of pipe 10 at all times.

The leading end of housing 19 is connected to a rotary support 26 uponwhich are pivotally mounted a pair of detector shoes 27 and 28, support26 being rotatable relative to housing 19 so that the detector shoesscan the entire inner surface of the pipeline in a helical pattern asthe inspection apparatus is propelled through the pipeline. A pair ofrubber wheels 29 are connected to each of the detector shoes for spacingthese shoes a relatively short distance from the inner wall of the pipeso that they do not frictionally engage the wall,

The leading end of support 26 is connected to a housing 30 whichencloses the motive means for rotating support 26 and detector shoes 27and 28. The leading end of housing 30 is connected to the trailing endof a housing 31 upon which are mounted a ilange 32, a spring 33, and

` a ring 34 which support a plurality of centralizing wheels 3S in amanner similar to that by which wheels 23 are supported. Housing 31encloses the instruments of the apparatus.

The inspection apparatus includes means for detecting liaws in thepipeline. Such means can be any one of several well-known devices suchas the type including a plurality of search units 36 which produce anelectrical output signal indicative of the presence and characteristicsof a flaw. The search units can be in the form of search coils embeddedin detector shoes 27 and 2S. The output of search units 36 is fed intosignal processing circuits 37. It is to be understood that, while apipeline can contain many aws, only certain ones may be of such aserious nature as to require repairing the pipeline. Thus, while searchunits 36 detect the presence of all flaws, the signal processingcircuits can be arranged to determine whether or not each detected aw isa serious flaw. If it is, then the signal processing circuits 37 producean output pulse which is fed to a one-shot multi-vibrator 38 connectedto actuate a relay driver 39 which in turn actuates a relay 40.

Coil 18 is connec-ted in parallel with a surge limiter 41 and a sourceof power such as a battery 42 of sufficient voltage to cause suflicientcurrent to flow through coil 18 so that the magnetic field of themagnetized portion of the pipeline can be readily detected by amagnetometer. Relay 4t) includes a movable contact 43 which cooperateswith a stationary contact 44 connected so that the output of the batteryis fed to coil 18 only when the movable contact engages the stationarycontact. When the multivibrator actuates the relay driver, movablecontact 43 momentarily engages stationary contact 44 to allow current toow from battery 42 to coil 18 for only a short period of time to preventthe magnetized portion of the pipe from being relatively long due to themovement of the electromagnet as it permanently magnetizes the pipe.

Because, in the embodiment illustrated in the drawings, theelectromagnet is axially spaced from the detector unit, the relay driveror one of the other components can include a time delay connected todelay energization of the electromagnet until the electromagnet ispositioned immediately adjacent to the portion of the pipelinecontaining the detected flaw.

A footage-inspected register 45 and a radial angle register 46 areconnected to the signal processing circuits 37 and are operative toprovide an indication of the point along the pipeline at which the ilawis located and the angular position of such aw, respectively, so that arepair crew can more readily locate that portion of the pipelinecontaining the flaw. A tape recorder 47 is actuated by the signalprocessing circuits to provide a magnetic record of the inspection.

As previously indicated, the apparatus shown in the drawing is only onemeans for carrying out the method of the invention. There are severalother means for carrying out the method. For example, where a shortsection of pipe is being inspected, it may be more practical to connectthe inspection apparatus to a cable which can be manually or otherwiseactuated to pull the inspection apparatus through the member beinginspected. The search units and signal processing circuits can beconnected to actuate a meter so that, when the flaw is encountered, theoperator can then manually close a switch to actuate the electromagnetto magnetize that portion of the member containing the flaw.

Further, in the embodiment illustrated, the pipeline ischaracteristically magnetized to produce a magnetic eld of a givenpolarity at the location of each aw. Other types of characteristicmagnetization can be employed. For example, the electromagnet can becontinuously energized as it passes through the pipeline. When a flaw isencountered, the direction of current flowing through coil 1S isreversed so that the plurality of the magnetic eld is also reversed.Under such circumstances, a aw would be indicated on a magnetometer bymovement of the needle to indicate a reversal of the field. This methodis advantageous in that small residual elds in pipeline 10 are erasedand thereby precludes noise on the search magnetometer. However, thismethod is disadvantageous because it requires a continuous applicationof power to the electromagnet.

It will be apparent to those skilled in the art that many changes can bemade without departing from the scope of invention as defined in theappended claims.

What is 4claimed is:

11. In apparatus for inspecting ferromagnetic tubular goods, saidapparatus being adapted to be propelled through the interior of saidgoods, the combination of magnetic means operative to characteristicallymagnetize portions of said tubular goods, at least one detector shoemounted to scan the inner wall of said goods to detect aws in those,portions being scanned, and means connected to said detector shoe andto said magnetic means to operate said magnetic means tocharacteristically magnetize those portions of said goods which containflaws.

2. Pipeline inspection apparatus comprising a housing means arranged tofreely move with a motive fluid through a pipeline, means supported bysaid housing means for detecting aws in said pipeline, and meanssupported by said housing means for characteristically magnetizing thosesections of said pipeline which .contain flaws.

3. Pipeline inspection apparatus comprising a housing means arranged tofreely move with a motive fluid through a pipeline, said housing meanssupporting an electromagnet, a source of direct current electricalpower, and a circuit means, said circuit means being connected to saidelectromagnet and to said source and operative to energize saidelectromagnet to magnetize those portions of said pipeline adjacent tosaid electromagnet as said housing moves through said pipeline, anddetecting means supported by said housing and operably connected to saidcircuit means for actuating the same to cause said pipeline to becharacteristically magnetized at the location of each aw.

4. Pipeline inspection apparatus comprising uid operated motive meansfor driving said apparatus through said pipeline, means for maintainingsaid apparatus substantially along the axis of said pipeline, magneticmeans operative to magnetize portions of said pipeline, said magneticmeans including a core having a coil thereon and having circular pole.pieces disposed at each end of the core to be transverse to thepipeline length in spaced apart relation and approaching the internalsurface of the pipeline, detecting means operative to detect flaws insaid pipeline, and means connected to said detecting means and saidmagnetic means for operating said magnetic means to characteristicallymagnetize those portions of said pipeline which contain flaws.

5. A method 'for marking the location of aws in a fiuid carrying tubularferromagnetic member, comprising simultaneously introducing a flawdetecting device and an electromagnet into said fluid for movementthrough said member, detecting the existence of a flaw 'by said flawdetecting device, and in response to detection of said flaw, actuatingsaid electromagnet with direct current to characteristically magnet-izesaid member to magnetically mark the location of said detected flaw.

6. A method for marking the location of a flaw in a ferromagneticpipeline, comprising simultaneously passing through said pipeline both aflaw detecting device and an electromagnet, detecting the existence offlaws by said tiaw detecting device and, in response to detection ofeach fiaw, energizing said electromagnet with direct current tocharacteristically magnetize said pipeline and thereby magnetically markthe location of each detected fiaw.

7. A method for inspecting a tubular ferromagnetic member to locateilaws and mark the position of the aws, comprising the steps of;

passing a flaw inspection device within said member;

magnetically marking on the inside of said member the location of a flawupon detection by said inspection device to enable magnetic sensing ofsaid magnetic mark from outside said member. 8. A method for inspectinga line of ferromagnetic pipe for aws, comprising the steps of;

locating a flaw by inspecting the inside of said pipeline, and

magnetizing the pipe wall from within said pipeline at the location oftlaw to a sufficient extent that the magnetic mark can be detected fromoutside said pipe. 9. A method for inspecting a line of ferromagneticpipe, comprising the steps of;

locating a flaw by internal inspection of the pipe with a iiawinspection device that travels through the pipe; marking the location ofthe aw by magnetizing a portion of the pipe adjacent the aw with amagnet-izing means carried by said flaw inspection device,

said magnetic mark being sucient for detection outside said pipe; and,magnetically scanning the outside of said pipe to detect said magneticmark and thereby locate said detective pipe portion. 1). A method forinspecting a line of ferromagnetic pipe disposed below the groundsurf-ace and extending substantially horizontal, comprising the stepsof;

locating a aw by internal inspection of the pipeline with a awinspection device that travels through t-he pipeline; marking thelocation of the Haw by magnetizing a portion of the pipe adjacent theflaw with a magnetizing means carried by said aw inspection device,

said magnetic mark being sufcient for detection at the ground surface;magnetically scanning the 'ground surface above said pipeline to detectthe magnetic mark and thereby locate said defective pipe portion. 11.Apparatus for inspecting a pipeline of ferromagnetic sections,comprising;

a housing means dimensioned to fit Within and move along the pipeline;centering means on said housing means for maintaining alignment -of thehousing axis substantially parallel to the pipeline axis; fluidresponsive means carried by said housing for propelling said housingmeans along the pipeline; instrumentation means mounted on said housingmeans and comprising;

a aw detection means having at least one search shoe; said housing meanshaving a support extending longitudinal of the pipeline and beingrotatably driven about said housing axis; la member pivotally attachedto said support and extending outward towards the pipe inner surface,substantially transverse to the axis of said housing means, said searchshoe being attached at the -outward end of said member to move towardthe internal pipe surface under the action of centrifugal force as saidsupport rotates; means for spacing said search shoe slightly from thepipe internal surface; said housing means having a magnetic eldproducing means including a core with circular pole pieces disposedtransverse to the pipe length in spaced apart relation and approachingthe internal surface of the pipe, and a coil on said core; saidinstrumentation means further comprising a D.C.

source for energizing said coil, and

:control circuit means for momentarily connecting said D.C. source tosaid coil upon detection of a flaw to magnetize the pipe adjacent thedetected flaw.

References Cited by the Examiner UNITED STATES PATENTS 6/1941 Smith324-34 X 5/1942 Billstein 324-37 X 5/1960 Newby 324-34 I6/ 1960Scherbatskoy 324-37 X R. B. LAPIN, Assistant Examiner.

1. IN APPARATUS FOR INSPECTING FERROMAGNETIC TUBULAR GOODS, SAIDAPPARATUS BEING ADAPTED TO BE PROPELLED THROUGH THE INTERIOR OF SAIDGOODS, THE COMBINATION OF MAGNETIC MEANS OPERATIVE TO CHARACTERISTICALLYMAGNETIZE PORTIONS OF SAID TUBULAR GOODS, AT LEAST ONE DETECTOR SHOEMOUNTED TO SCAN THE INNER WALL OF SAID GOODS TO DETECT FLAWS IN THOSEPORTIONS BEING SCANNED, AND MEANS CONNECTED TO SAID DETECTOR SHOE AND TOSAID MAGNETIC MEANS TO OPERATE SAID MAGNETIC MEANS TO CHARACTERISTICALLYMAGNETIZE THOSE PORTIONS OF SAID GOODS WHICH CONTAIN FLAWS.